1. Field of the Invention
This invention relates to electronic musical instruments in which a desired envelope waveshape in digital form can easily be obtained through utilization of coefficients relating to attack and decay times.
2. Description of the Prior Art
Envelope signal generators for use in conventional electronic musical instruments are divided into those of an analog system that make use of the charge discharge characteristic of a time constant circuit composed of a capacitor and a resistor and those of a digital system that quantization step information is stored. In the analog system, however, various characteristics are prepared for attack, decay, sustain and release portions forming an envelope and are switched by combining many resistors, diodes and change-over switches, but this inevitably introduces complexity in circuit arrangement. In contrast thereto, the digital system has such a shortcoming that in order to increase the number of quantization steps and prepare characteristics of various attack and decay time, an enormous storage capacity is needed for storing such information.